The objectives of this project are to recruit sufficient volunteer donors to support the red cell, white cell, and platelet transfusion needs of Clinical Center patients, and to manage the recruitment aspects and maintain the files of a large registry of unrelated potential bone marrow donors. Specific objectives include the administration and expansion of donor recruitment programs for voluntary whole blood donors, voluntary plateletpheresis and leukapheresis donors, research cytapheresis and plasma donors, and unrelated volunteer bone marrow donors. File maintenance shall include updating and searching the listings of a minimum of 5,000 active HLA-typed volunteer apheresis donors, and updating, searching and coordinating the marrow harvests from a listing of a minimum of 10,000 HLA- typed bone marrow donors. Lastly, objectives shall include the performance of sufficient plateletpheresis and leukapheresis procedures to meet the transfusion needs of Clinical Center patients.